package com.witframework.util;

import java.security.MessageDigest;

import org.apache.commons.codec.EncoderException;
import org.apache.commons.codec.binary.Base64;



/**
 * String Utility Class This is used to encode passwords programmatically
 *
 */
public class StringDigest {
    /**
     * Encode a string using algorithm specified in web.xml and return the
     * resulting encrypted password. If exception, the plain credentials
     * string is returned
     *
     * @param password Password or other credentials to use in authenticating
     *        this username
     * @param algorithm Algorithm used to do the digest
     *
     * @return encypted password based on the algorithm.
     */
    public static String encodePassword(String password, String algorithm) {
        byte[] unencodedPassword = password.getBytes();
        MessageDigest md = null;
        try {
            // first create an instance, given the provider
            md = MessageDigest.getInstance(algorithm);
        } catch (Exception e) {
        	e.printStackTrace();
            return password;
        }
        md.reset();
        // call the update method one or more times
        // (useful when you don't know the size of your data, eg. stream)
        md.update(unencodedPassword);
        // now calculate the hash
        byte[] encodedPassword = md.digest();
        StringBuffer buf = new StringBuffer();
        for (int i = 0; i < encodedPassword.length; i++) {
            if ((encodedPassword[i] & 0xff) < 0x10) {
                buf.append("0");
            }
            buf.append(Long.toString(encodedPassword[i] & 0xff, 16));
        }
        return buf.toString();
    }

    /**
     * Encode a string using Base64 encoding. Used when storing passwords
     * as cookies.
     *
     * This is weak encoding in that anyone can use the decodeString
     * routine to reverse the encoding.
     *
     * @param str
     * @return String
     * @throws EncoderException 
     */
    public static String encodeString(String str) throws EncoderException  {    	
        return new String(Base64.encodeBase64(str.getBytes()));
    }
    public static String encodeBytes(byte[] str) throws EncoderException  {    	
    	return new String(Base64.encodeBase64(str));
    }

    /**
     * Decode a string using Base64 encoding.
     *
     * @param str
     * @return String
     */
    public static String decodeString(String str) {    	
        try {
            return new String(Base64.decodeBase64(str.getBytes()));
        } catch (Exception io) {
        	throw new RuntimeException(io.getMessage(), io.getCause());
        }
    }
    public static byte[] decodeBytes(String str) {
    	
        try {
            return Base64.decodeBase64(str.getBytes());
        } catch (Exception io) {
        	throw new RuntimeException(io.getMessage(), io.getCause());
        }
    }
    public static void main(String[] args) throws EncoderException {
      System.out.println(StringDigest.encodePassword("wuxinyang","SHA"));
      System.out.println(StringDigest.encodePassword("wuxinyang","MD5"));
      System.out.println(StringDigest.encodeString("wuxinyang"));
      System.out.println(StringDigest.decodeString("d3V4aW55YW5n"));
	}
}
